val numbers = arrayOf(1, 2, 3, 4, 5)
// 计算累积索引加权和, 累积索引加权和: [0, 1, 5, 14, 30, 55]
numbers.runningFoldIndexed(0) { index, acc, element -> acc + element * (index + 1) }.forEach {
    _console.log(it)
}